In the conventional DC-PDP wherein light-emission generated by cold cathode discharge is utilized for display, the discharge initiation voltage and discharge maintaining voltage are high. Therefore, not only is it difficult to connect such DC-PDP directly to peripheral circuit elements such as LSI, but also a large output is required for obtaining sufficient display light-emission. This leads to a reduction in the efficiency of the conventional DC-PDP. The reason for this is that in the conventional DC-PDP, cathode materials having a high work function, such as iron, nickel, chromium and alloys thereof are used, and hence the cathode fall voltage constituting the major portion of discharge voltage in the cold cathode discharge is increased.
As a method of decreasing the cathode fall voltage, materials having low work functions are often used for the preparation of cathodes. Furthermore, since the cathode is always subject to ion collision during the operation, it is necessary that cathode materials be used which have high abrasion resistance against ion collision. However, when materials having high melting points and suitable for use as the cathodes are selected from cathode materials having low work functions and high abrasion resistance against ion collision, it is difficult to prepare the cathode by conventional methods such as printing, vapor-deposition and plating.
One of the reasons for this diffuculty is that when a high melting point material as described above is converted into ink form by the use of a vehicle and printed on the substrate of DC-PDP or cathode substrate by thick film printing, it is necessary to melt the high melting point material by heating at high temperatures and to deposit it onto the substrate, but the heating of a DC-PDP having a thin and broad flat structure at such high temperatures may cause the deformation of the structure. Hence a sufficient heat treatment cannot be applied, giving rise to the problem that metal particles of the high melting point material are only weakly bonded together.
Also, in the case of vapor-deposition or plating, it is not possible to prepare a cathode having a sufficient thickness, and hence the cathode formed has poor durability and a short service life.